Terephthalic based unsaturated polyesters

ABSTRACT

A PROCESS IS DISCLOSED FOR THE PREPARATION OF TEREPHTHALATE BASED UNSATURATED POLYESTERS BY FIRST REACTING A MONOUNSATURATED DICARBOXYLIC ACID ANHYDRIDE HAVING FROM 4-10 CARBON ATOMS WITH A TEREPHTHALIC ACID GLYCOL ESTER HAVING THE GENERAL FORMULA:   1,4-BIS(HO-R-OOC-)BENZENE   WHEREIN R IS C2 TO C6 ALKYLENE TO FORM A GLYCOL ESTERNONO UNSATURATED ACID ADDUCT AND THEN REACTING THIS ADDUCT WITH AN OXIDE HAVING THE GENERAL FORMULA:   R1-OXIRANE   WHERE R1 IS H OR AN ORGANIC RADICAL HAVING FROM 1 TO 8 CARBON ATOMS. THE RESULTING POLYESTER IS USEFUL IN PREPARING PROTECTIVE COATING AND PLASTICS WHEN BLENDED WITH AN ETHYLENICALLY UNSATURATED MONOMER AND AN ADDITION POLYMERIZATION INITIATOR SYSTEM.

United States Patent 3,804,921 TEREPHTHALIC BASED UNSATURATED POLYESTERSSaunders E. Jamison, Summit, N.J., assignor to Celanese Corporation, NewYork, NY.

No Drawing. Original application Apr. 13, 1970, Ser. No. 32,497, nowPatent No. 3,725,461. Diw'ded and this application Sept. 13, 1972, Ser.No. 288,866

Int. Cl. 008E 21/00 US. Cl. 260-861 3 Claims ABSTRACT OF THE DISCLOSUREA process is disclosed for the preparation of terephthalate basedunsaturated polyesters by first reacting a mono unsaturated dicarboxylicacid anhydride having from 4-10 carbon atoms with a terephthalic acidglycol ester having the general formula:

wherein R is C to C alkylene to form a glycol estermono unsaturated acidadduct and then reacting this adduct with an oxide having the generalformula:

wherein R is H or an organic radical having from 1 to 8 carbon atoms.The resulting polyester is useful in preparing protective coatings andplastics when blended with an ethylenically unsaturated monomer and anaddition polymerization initiator system.

This is a division of application Ser. No. 32,497, filed Apr. 13, 1970,now Pat. No. 3,725,461, issued Apr. 3, 1973.

BACKGROUND OF INVENTION The field of art to which this inventionpertains is unsaturated polyester, particularly terephthalic acid-basedunsaturated polyesters.

Thermosetting unsaturated polyester resins are well known in the art.Typically, they are based upon the reaction of a polyol and a polybasicethylenically unsaturated polyacid. Due to the tendency of terephthalicacid and its alkyl esters to sublime when heated, attempts toincorporate terephthalate moieties into unsaturated polyester resinshave been unsuccessful.

SUMMARY OF INVENTION Surprisingly, it has now been found that, unlikealkyl esters, bis(alkylene glycol) esters of terephthalic acid do notsublime when attempts are made to incorporate them into unsaturatedpolyester formulations. According to the process of this invention, amono-unsaturated dicarboxylic acid anhydride is reacted with aterephthalic acid glycol ester having the general formula:

wherein R is C to C alkylene, to form a glycol ester mono-unsaturatedacid adduct. The adduct is then further reacted with an oxide having thegeneral formula:

wherein R is H or an organic radical having from I to 8 carbon atoms.

3,804,921 Patented Apr. 16, 1974 ice DESCRIPTION OF INVENTION Theterephthalic acid glycol ester useful in this invention has the generalformula:

O O HO-R-O-ii-Q-ii-O-R-CH wherein R is a C to C alkylene containing onlycarbon and hydrogen. Thus the ethyl, propyl, butyl, pentyl, or hexylglycol esters of terephthalic acid can be used. Formation of the C to Calkylene glycol esters can be carried out by any of several well-knownmethods. Included is the reaction of an alkylene oxide such as ethylene0r propylene oxide with terephthalic acid. Likewise, free terephthalicacid can be esterified with the desired glycol or a dialkylterephthalate can be transesterified with the desired glycol.

Reacted with each mol of the terephthalic acid glycol ester is about 2mols of a mono-unsaturated dicarboxylic acid anhydride having from 4 toabout 10 carbon atoms per molecule and containing no other hydroxyl oracid reactive groups. Examples of this acid include maleic anhydride andcitraconic anhydride. [The compound resulting from the reaction of theterephthalic acid glycol ester and the mono unsaturated acid anhydrideis hereinafter referred to as a glycol ester-mono unsaturated acidadduct] This reaction is carried out at about C. to 150 C. preferablyabout C. to C.

The oxides useful in preparing the unsaturated polyester of thisinvention can be either alkylene oxides or they can be mono glycidylethers. Examples of the alkylene oxides include, ethylene oxide,propylene oxide, butylene oxide, styrene oxide, and the like. The monoglycidyl ethers include butyl glycidyl ether, pentyl glycidyl ether,isopropyl glycidyl ether, phenyl glycidyl ether and the like. Preferredamong the above oxides are those having the general formula wherein R isH or an organic radical having from 1 to 8 carbon atoms. [It isunderstood that in the above formula R can include an ether group] Mostpreferred among the oxides are ethylene oxide and propylene oxide.

The oxide is reacted with the above glycol ester-mono unsaturated acidadduct in amount equal to about one mol of oxide for each mol of reactedunsaturated acid anhydride to form the unsaturated polyester resins ofthis invention. Thus in the preferred reaction about one mol of theterephthalic acid glycol ester is reacted with about two mols of themono unsaturated acid anhydride and the resulting product is thenreacted with about two mols of oxide. This reaction should be carriedout below the boiling point of the particular oxide that is used. Ininstances where a catalyst such as a tertiary amine, quaternary aminesalt, thiol, mercaptan or disulfide is used temperatures in the range ofabout 25 C. to 110 C. can 'be used depending, of course, on the oxideboiling point. In instances where no catalyst is used temperatures ashigh as 75' C. to C. may be required.

Blended with the terephthalic based unsaturated polyester is a monoethylenically unsaturated monomer which is polymerizable with thepreviously described mono unsaturated acid hydride. The monomer may beany one or more of a wide variety, such as vinylidene chloride and thevinyl esters of fatty acids having from 1 to 18 carbon atoms, includingvinyl acetate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyloleate, and vinyl stearate. Esters of acrylic acid or of methacrylicacid with alcohols having from 1 to 18 carbon atoms may likewise beemployed. Examples include methyl acrylate or methacrylate, ethylacrylate or methacrylate, propyl acrylate or methacrylate, isopropylacrylate or methacrylate, the various butyl acrylates or methacrylates,cyclohexyl acrylate or methacrylate, Z-ethylhexyl acrylate ormethacrylate, benzyl acrylate or methacrylate, phenyl acrylate ormethacrylate n-hexyl, n-octyl, t-octyl, dodecyl, hexadecyl, or octadecylacrylates or methacrylates. Acrylonitrile, methacrylonitrile,acrylamide, methacrylamide, styrene, methyl styrene, vinyl toluenes,acrylic acid, acrylic acid anhydride, methacrylic acid, methacrylicanhydride, fumaric acid, crotonic acid, allyl acetate, glycidylmethacrylate, t-butylaminoethyl methacrylate, hydroxyalkyl acrylates ormethacrylates such as ,B-hydroxyethyl methacrylate, fl-hydroxypropylmethacrylate, fi-hydroxyethyl vinyl ether, fl-hydroxyethyl vinylsulfide, N-vinyl-2-pyrrolidone, N,N-dimethylaminoethyl methacrylate,etc.

The unsaturated polyester can be reduced to about 80 to about 30 weightpercent solids in the ethylenically unsaturated monomer, preferablyabout 50 to about 70% solids.

In order to cure the above blends a catalyst or initiator system shouldbe incorporated therein using compositions and amounts well known in theart. Generally about 0.1 to 25% [preferably about 0.25 to 7.5 weightpercent], based on the total weight of the unsaturated polyester and theethylenically unsaturated monomer, of a free radical polymerizationinitiator system is incorporated into these blends. The first portion ofthis system is an organic addition polymerization initiator or catalyst.Examples include organic peroxides and other free radical sources suchas benzoyl peroxide, peracetic acid, methyl ethyl ketone peroxide,cyclohexane peroxide, cyclohexyl hydroperoxide, cumene hydroperoxide,tertiary butyl perbenzoate, tertiary butyl peroctoate, dicumyl peroxide,azobisisobutyronitrile, ditertiary butyl peroxide, and so on. Also addedas the other portion of this system is an activator for the aboveinitiator. These activators are of two main types-tertiary amine anddryer typeand may be added either alone or together. Included among thetertiary amines are N,N diethyl aniline, N,N dimethyl aniline, triethylamine, etc. Among the dryer types are included cobalt naphthenate,cobalt ethyl hexoate and other well known driers commonly used to aidthe air drying of alkyd resins. Finally, miscellaneous activatorsincluding the mercaptans such as lauryl mercaptan, benzoin and biacetylcan also be used.

Solutions prepared in the above manner have a wide variety of uses ineither their pigmented or unpigmented forms. They can be used ascorrosion resistant reinforced plastics, in molded boat hulls, and thelike. Likewise they can be used as protective coatings.

In the following examples parts and percentages unless otherwise statedare by weight.

EXAMPLE I An unsaturated polyester having the formula:

was prepared by reacting 1 mol of bis(2-hydroxyethyl) terephthalate(BHET) with 2 mols of maleic anhydride and then further reacting theresulting product with 2 mols of propylene oxide. The BHET was preparedby condensing at 160 C. in a sealed vessel ethylene oxide andterephthalic acid in the presence of triethylamine in a mixture of about20% ethyl benzene and xylene; extracting the thus formed diester withwater and recrystallizing from a water mixture. Maleic anhydride wasadded to the BHET and the two materials were reacted at C. to C. forabout 30 minutes. Propylene oxide was added to the light straw-coloredsyrup thus obtained and coreaction was carried out at 30 C. producing afaintly greenish syrup. At no time during the course of any of the abovereactions was sublimination of any kind noted.

50 parts of the above unsaturated polyester were blended with 50 partsof styrene. To 10 grams of this blend were added 15 drops of 6% cobaltnaphthenate and 30 drops of 60% methyl ethyl ketone peroxide. Whenallowed to stand at room temperature for ten hours a clear tough plasticmaterial resulted.

EXAMPLE II Using the same procedure as in Example I, a blend containing50 parts of the unsaturated polyester prepared in Example I and 50 partsof diallyl phthalate was prepared. Catalysis with cobalt naphthenate andmethyl ethyl ketone peroxide as in Example I produced a clear hardsolid.

EXAMPLE HI In a similar manner blends of the unsaturated polyester ofExample I and methyl methacrylate, methyl acrylate and vinyl acetatewere prepared and cured. These cured products were all tough and hard.

It is to be understood that the foregoing detailed description is givenmerely by way of illustration and that many variations may be madetherein without departing from the spirit of the invention.

The embodiments of this invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A process for preparing a curable unsaturated polyester solution,which comprises:

(A) reacting, at about 75 C. to about C., about 2.0 mols of a monounsaturated dicarboxylic acid anhydride having from about 4-10 carbonatoms per molecule and containing no other hydroxyl reacting groups witha terephthalic acid glycol ester having the general formula:

wherein R is C; to C alkyl and contains only carbon and hydrogen to forma glycol ester-mono unsaturated acid adduct; and

(B) reacting at about 25 C. to about 150 C. said glycol adduct withabout 2.0 mols of an oxide having the general formula:

wherein R is H, a hydrocarbyl radical having 1 to 8 carbon atoms, or ahydrocarbyloxymethyl radical having 1 to 8 carbon atoms to form anunsaturated polyester; and

(C) blending said polyester with an ethylenically unsaturated monomerand a polymerization initiator system.

5 2. The process of claim 1 wherein said monomer is styrene.

3. The process of claim 1 wherein R is CH and R is 0 H References CitedUNITED STATES PATENTS HAROLD D. ANDERSON, Primary Examiner 6 E. A.NEILSEN, Assistant Examiner us. 01. x41.

I UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,804, 921 Dated A ril l6 1974 Inventor(s) Saunders E. Jamison It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Column 2, line 10-, delete-- 9 9 "HQ-R-O-G-4 c'-o-R-cH"--and insertiolumn 3, line 1. delete--"hydride"--and insert-"anhydride".,

Signed and sealed this 17th day of September 197 (SEAL) Attest:

MCCOY M. GIBSON JR. Attesting Officer C. MARSHALL DANN Commissioner ofPatents USCOMM-DC 50376-P69 FORM PO-1050 (1069) h us. GOVERNMENTPRINTING OFFICE: I969 O366-334

